Three additional arrests have been made in connection with the Boston Marathon bombing case, Boston police said Wednesday. The three who were detained were not immediately identified but were taken into custody by the FBI, police said. Investigators have been looking into whether other people conspired with Tamerlan and Dzhokhar Tsarnaev, the brothers who allegedly detonated two bombs at the Boston Marathon on April 15. Following the announcement of the arrests, the Boston Police Department said in a tweet: “Please be advised there is no threat to the public.” PHOTOS: Boston Marathon bombing Three people were killed and more than 260 injured when the bombs exploded near the marathon finish line.

April 15, 2013 | By Michael Muskal, Richard A. Serrano and Joe Tanfani, This post has been corrected and updated, as indicated below.

BOSTON--- Two bombs shattered the celebratory mood of the Boston Marathon Monday, turning the finish line into a zone of carnage that left at least three dead and more than 130 injured. The explosions hours into the 117th running of the iconic 26.2-mile race came well after the elite runners had finished, but near the time when the bulk of the about 27,000 runners were laboring toward the finish line. Two bombs hundreds of yards apart went off within seconds of each other on what was also Patriots Day. Dazed and bloodied victims walked around seeking help as officials rushed to their aid, taking them to one of the medical tents that dot any marathon route.

Both bombs that exploded outside an Atlanta abortion clinic last week were made of dynamite, which is regulated and not often found in amateur bombs, federal law enforcement officials said. Each bomb may have contained 10 to 20 sticks of dynamite, these officials said on condition of anonymity. Legal buyers of dynamite are required to get a federal permit to transport it between states. The presence of "high-grade commercial dynamite" was reported by CBS News, citing unidentified sources.

WASHINGTON -- Investigators believe that the two homemade bombs used in the Boston Marathon blasts were triggered by long-range remote controls for toy cars. A joint FBI and Department of Homeland Security intelligence bulletin sent to state and local law enforcement Tuesday night said the bombs likely included components taken from remote-controlled toy cars, and were more sophisticated than previously believed. After combing the blast sites on Boylston Street for evidence, investigators have finished a preliminary reconstruction of the bombs that killed three people and injured more than 260 runners and bystanders near the finish line of the Patriots Day race on April 15. FULL COVERAGE: Boston Marathon attack “Based on preliminary analysis of recovered evidence, each device likely incorporated an electrical fusing system using components from remote control toy cars such as a transmitter and receiver pair operating at 2.4 GHz, an electronic speed control used as the switch mechanism and sub-C rechargeable battery packs at the power source,” read the bulletin, according to an official.

Two pipe bombs sent late last month to offices in Kansas City may be linked to a suspect who has been sending increasingly threatening letters to financial institutions since at least 2005. Officials have suggested in both cases that the devices were not working bombs that could have exploded. The devices appear to be a sign that the suspect, who calls himself "The Bishop," may be closer to sending live bombs, said Fred Burton, a counterterrorism expert.

Two teenage boys have been charged with setting off two homemade bombs inside a Wal-Mart filled with holiday shoppers, authorities said. Hundreds of customers were evacuated from the store when the acid bombs detonated Saturday. At least eight people were treated for irritation to their eyes and throat or ringing in their ears, authorities said.

A 17-year-old Antelope Valley High School student was arrested Friday morning for possessing two pipe bombs on campus, Los Angeles County sheriff's deputies said. Sgt. Bob Denham said a 16-year-old student spotted one of the bombs while observing the 17-year-old lighting gun powder on a table. The younger boy took the bomb and gave it to campus security. A sheriff's deputy assigned to the school contacted the older boy and found the second pipe bomb in his pants pocket.

WASHINGTON - The FBI has found female DNA on at least one of the two homemade bombs detonated during the Boston Marathon on April 15, complicating the task of identifying how and where the deadly devices were constructed. The presence of genetic material does not necessarily mean a woman helped build the pressure-cooker bombs that killed three people and injured more than 260 others, said a law enforcement official, who discussed the discovery on condition of anonymity because the investigation is ongoing.

The season's first hailstorm in parts of southern Lebanon triggered unexploded bomblets from cluster bombs dropped in last year's war between Hezbollah militants and Israel. No injuries were reported. Dalya Farran, a spokeswoman for the U.N. Mine Action Coordination Center, confirmed a state-run National News Agency report that many cluster bombs exploded when they were hit by hailstones in villages near the town of Marjayoun.

Police in Ireland said they discovered two rudimentary but potentially lethal bombs that they linked to Continuity IRA, one of the dissident republican groups opposed to the Northern Ireland peace process. The devices were part of a haul confiscated in a van at a roadside checkpoint in County Tipperary on Sunday evening. Police were questioning the driver, a 39-year-old man from Limerick.